Eisenia fetida

Classification

Eukaryotes are organisms that have a true
nucleolus and membrane-bound organelles.

Kingdom

Animalia

Organisms under the
kingdom Animalia are
defined by being multicellular and heterotrophic. They also
lack cell walls. These
organisms are almost all motile.

Phylum

Annelida

Annelida comes from Latin meaning "little
rings," therefore this is the phylum of ringed worms - this means
that the worms in this phylum have bodies broken down in to small
compartments or
segments. They are
coelomates and have a
digestive system that runs from the head to anus.

Class

Oligochaeta

Like the name implies, this class has "few"
chaetae or setae. They also
lack parapodia and have relatively
simple head with no sensory appendages. All of the organisms
in this class are
hermaphrodic.

Order

Haplotaxida

This
order is mostly comprised of aquatic
worms, but Eisenia fetida
fits into this order because the
defining feature is that the male
funnels at least one segment
in front of the segment that
contains the testes, or male pores.

Family

Lumbricidae

Within the
order of Haplotaxida, the
Lumbricidae family is defined by
having dorsal setal pairs that are
located ventrally, laterally, or
dorsolaterally. It also
contains organisms with a
saddle-shaped
clitellum which
occupies 4-32 segments (Brinkhurst). The
greatest differentiation between the
families of Haplotaxida are based on
the general area of specific
structures such as gizzards, sperm
pores, or the clitellum. The
location of these structures are
generally given in relation to the
segments of the worm body. For
example, Eisenia fetida has
sperm pores in segment 15, a
clitellum which is variable from
segments 26 or 27 to segments 32 or
33, and a gizzard in segments 17-18.

Genus

Eisenia

Eisenia is
believed to be derived from American
zoologist Gustav Eisen's last name.
He worked with earthworms in the
United States in the seventeenth and
eighteenth centuries. One of
his published works was
Researches in American Oligochaetea
which was published in 1900.

Species

Eisenia fetida
(Savigny,
1826)

fetidacomes from the Latin word "fetid" which means "foul smelling."
This refers to Eisenia fetida's
ability to eject a foul
smelling liquid from its body if it is roughly handled or fears
predation.

Some people think worms are gross, but if that's not you, Eisenia
fetida might be too nice for you. Check out some nasty
parasitic worms that other students at
UW-La Crosse have studied
here:

Phylogenetic Trees

These two phylogenetic trees above show the classification of taxa
in the phylum Annelida. The 1997 Westheide study shows a
classification built upon morphological characteristics such as the
presence or absence of nuchal organs and parapodia. Eisenia fetida
would fall within the general category of Clitellata in both of
these diagrams.

The other phylogenetic tree is from another 1997 study; this one by
McHugh. These category placements are based upon data from
molecular tools. The specific molecular information analyzed
was elongation factor 1 alpha in a parsimony analysis. Not only does it show a broader view which
includes several other phylum in addition to the Annelids, but it
has a somewhat different breakdown of the Annelid phylum (black
lines.) Stermaspis is a genus that is wholly composes the family
Sternaspidae. This genus is polychaeted and therefore would not be
categorized next to the Oligochaetaes in the tree to the left. Also,
Echiura are “spoon worms” that, even though they are categorized as
Annelids, have no segments. These two taxa demonstrate the
additional knowledge that can be received from molecular tools and
there importance in classification today.

Another interesting note related to molecular tools comes from
Eisenia fetida’s sibling species, Eisenia andrei. This species is
considered a molecular species because without molecular tools, it
cannot be distinguished from Eisenia fetida. Therefore, its
discovery as a separate species has only recently been discovered.
The tool used in distinguishing these two obviously closely related
species is electrophoresis.